1. Field of the Invention
The present invention relates to a technique for supplying fuel to an internal combustion engine.
2. Description of the Related Art
There have been proposed techniques for selectively supplying each of a high octane number fuel and a low octane number fuel separated from a raw fuel to an internal combustion engine (Refer to Japanese Patent Application Laid-Open No. 2007-278298 and Japanese Patent Application Laid-Open No. 2009-144720).
Moreover, there has been proposed a technique for preventing air from entering a tank for storing a high octane number fuel, which is caused by low volatile of the high octane number fuel in comparison with the raw fuel (Refer to Japanese Patent Application Laid-Open No. 2009-203909). Specifically, a device is configured so that vaporized fuel is supplied from a raw fuel tank to the high octane number fuel tank and then supplied from the high octane number fuel tank to a charcoal canister.
As the adsorption capacity of the canister is greater, a larger amount of vaporized fuel is able to be efficiently used for the running of the internal combustion engine. Due to a restriction on a space where the canister is mounted in a vehicle, however, the adsorption capacity is limited. Accordingly, in the case where a large amount of vaporized fuel occurs, the vaporized fuel which has been unsuccessfully adsorbed to the canister is discharged to the outside of the vehicle and thus wasted.